1. Field of the Invention
The present invention relates to an improved coordinates input apparatus, and more particularly, to a pointing apparatus that can be used without the need for special operating space.
2. Description of Related Art
In recent years, easy-to-operate pointing apparatus have come to be widely used instead of keyboards as an input means for computers and the like.
For example, a mouse or a digitizer can be used with desktop computers and the like.
However, the laptop and other portable computers that have become popular in recent years are often used outdoors, in vehicles, and so forth, that is, in locations where there is no flat surface on which to rest the computer. As a result, there is often little or no space in which to operate a pointing apparatus such as a mouse or digitizer. Additionally, as portable computers have become more compact the need for the pointing apparatus to become smaller has grown as well.
Additionally, cellular telephones have come to be equipped with a pointing apparatus. Given the small size of cell phones, the pointing apparatuses used on these devices are required to be even smaller than those used on portable computers and the like.
In response to such requirements, a pointing apparatus that tilts when pressed and the angle of tilt sensed has been suggested as one type of suitable pointing apparatus that is compact and requires very little space to operate.
A description of such a conventional compact pointing apparatus will now be given with reference to FIGS. 1, 2, 3 and 4.
FIG. 1 is a diagram showing a front cross-sectional view of a conventional pointing apparatus illustrating a state in which the key top operating portion of the apparatus is substantially vertical. FIG. 2 is a diagram showing a front cross-sectional view of a conventional pointing apparatus illustrating a state in which the key top operating portion of the apparatus is tilted. FIG. 3 is a diagram illustrating a spatial relation between a magnet and a magnetoelectric transducer of the pointing apparatus shown in FIGS. 1 and 2. FIG. 4 is a diagram showing a side view of the magnet and magnetoelectric transducer of FIG. 3.
According to the conventional art, a pointing apparatus 1 comprises an operating part 2, a pressure part 3 and a coordinates sensor 4.
The operating part 2 comprises a key top 2a, a stick 2b fixedly mounted to one end part of the key top 2a, and a holder 2c composed of two halves that form a sphere when joined together.
The pressure part 3 comprises a slider 3a movable in a vertical direction along a frame 5 and a coil spring 3b that continuously presses the slider 3a in a downward direction.
The coordinates sensor 4 comprises a magnet 4a provided on an interior of the holder 2c and a plurality of magnetoelectric transducers 4b mounted on a printed circuit board 6 bonded to a bottom surface of the frame 5, the magnetoelectric transducers 4b being recessedly mounted in a bottom surface of the holder 2c. It should be noted that there are actually four magnetoelectric transducers 4b-1 through 4b-4 displaced a certain distance from the center line of the magnet 4a, as can be seen in FIG. 3.
In the pointing apparatus 1 having the structure described above, pressing and moving the key top 2a manually slides the slider 3a upward against the spring force of the coil spring 3b and, as shown in FIG. 2, the stick 2b is tilted in a given direction. At this time, the magnet 4a built into the holder 2c is tilted with respect to the magnetoelectric transducer 4b mounted on the printed circuit board 6.
Then, by releasing the key top 2a, the spring force of the compressed coil spring 3b returns the key top 2a to an original position before it was manipulated, thus returning the positional relation between the magnet 4a and the magnetoelectric transducer 4b to an initial state as well.
A description will now be given of the principle upon which the coordinates detector of the pointing apparatus 1 operates.
In a case in which the stick 2b is perpendicular to the printed circuit board 6 as shown in FIG. 1, as shown by the solid line in FIG. 4 the magnet 4a is separated from the four magnetoelectric transducers 4b (shown as 4b-1 through 4b-4 in FIG. 3) by a certain distance, and accordingly the magnetic field imparted to the magnetoelectric transducers 4b-1 through 4b-4 is essentially equal, so that for example, if the direction from which the magnetic field is sensed is perpendicular to the printed circuit board 6, then the sensed magnetic field direction components B1 through B4 of the magnetic flux density through the magnetoelectric transducers 4b-1 through 4b-4 would be substantially equal, and thus the output voltage of the magnetoelectric transducers would also be essentially equal.
By contrast, if the stick 2b is tilted with respect to the printed circuit board 6 as shown in FIG. 2, then the distance separating the magnet 4a from the magneto-electric elements 4b changes as indicated by the dashed line in FIG. 4. In the case of FIG. 4, the magnet 4a simultaneously approaches the magnetoelectric transducer 4b-1 and moves further away from the magnetoelectric transducer 4b-3, so the sensed magnetic field direction component B1 increases while the sensed magnetic field direction component B3 decreases and the output voltages from the magnetoelectric transducers 4b-1 and 4b-3 change as well, with an angle of inclination xcex8 of the key top 2a deduced from a calculation of the difference in output between the magnetoelectric transducers 4b-1 and 4b-3 and further converted into an X-axis coordinate value for the purpose of moving a cursor on a display (coordinate space). Similarly, by calculating the difference in output voltages between the magnetoelectric transducers 4b-2 and 4b-4 the angle of inclination xcex8 of the key top 2a can be converted in a Y-axis coordinate value. That is, XY coordinate values can be obtained when the stick 2b tilts in a given direction based on the direction and angle of that tilt. These XY coordinates are input into a computer and the direction, extent and speed of movement of the pointer or cursor then displayed on the display.
However, with the conventional pointing apparatus as described above, efforts to further miniaturize the pointing apparatus such as for example by shrinking the magnet and magnetoelectric transducers, has diminished the strength of the magnetic field generated and has led to a situation in which dimensional tolerances in the magnetoelectric transducers show up as unevenness in the performance of the finished apparatus with increased frequency, which is undesirable. Additionally, other measures to reduce the size of the pointing apparatus such as, for example, reducing the distance between the magnet and the magnetoelectric transducers and reducing the distance between each of the plurality of magnetoelectric transducers, has led to a situation in which the magnet and the magnetoelectric transducers physically interfere with each other, that is, the magnet collides with the magnetoelectric transducer when the magnet is tilted during operation of the pointing apparatus.
Accordingly, there are physical limitations to the reduction in the size of the components of the pointing apparatus attendant upon efforts to make personal computers, cell phones and the like more compact.
Accordingly, it is an object of the present invention to provide an improved and useful coordinates input apparatus in which the above-described disadvantage is eliminated, and more specifically, to provide an improved and useful coordinates input apparatus capable of accommodating further reductions in size.
The above-described object of the present invention is achieved by a coordinates input apparatus for designating a particular set of coordinates in three-dimensional space, the coordinates input apparatus comprising:
a substantially box-like frame;
an operating part tiltably positioned within the frame;
a printed circuit board supporting the frame;
a magnet;
a plurality of magnetoelectric transducers; and
a magnetic plate,
the magnet and the plurality of magnetoelectric transducers fixedly mounted on an upper surface of the printed circuit board opposite the magnetic plate, the magnet disposed so that one pole faces the magnetic plate, the magnetic plate disposed on a lower surface of the operating part opposite the magnet and tiltably supported by the frame via the operating part, the plurality of magnetoelectric transducers disposed around an outer rim of the magnet and outputting voltage signals indicating voltage values that vary according to a change in distance between the magnetoelectric transducers and the magnetic plate, such that the voltage signals indicate a set of coordinates in three-dimensional space.
According to this aspect of the invention, the coordinates input apparatus can be made thinner and more compact than is the case with the conventional art.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.